Quick couplings with displaceable inner parts are already well known. However, the present unit is to be used in connection with a pressure source, preferably for air, with the aid of which tools, elements and the like, are to be operated. The unit supplies the medium in question, conducted via a hose from the unit to the tool in question or the like. The unit can also include a nozzle, for example a nozzle for air blasting. The nozzle can be connected to a suitable pressure source via a hose or another line.